The present invention concerns radio-frequency identification devices, particularly related assembly methods and structures for modules in such devices.
Radio-frequency identification (RFID) devices are used in a variety of applications to facilitate the identification and tracking of people, objects, and animals. Each device, also known as a tag or smart card, can be attached to a person, object, or animal. The devices typically include an antenna coil, radio circuitry, and a memory, enabling them not only to receive radio-frequency signals from a reader or interrogation device, but also to send back signals representing the data in their memories. The data, generally a unique identification number, can then be used with a computerized database to associate the tagged person, object, or animal with other data, such as price, shipping, inventory, or owner information.
One problem with RFID devices or tags concerns manufacturing cost. In particular, the inventor recognized that some tag designs use a module requiring three external connections, instead of two as do many other designs. For example, one such design uses a module that has three external terminals A, B, and C, and requires connection of an antenna coil between terminals A and C and connection of one external capacitor between terminals A and B and another external capacitor between terminals B and C. Although the two capacitors in the design provide an increased communication range, the additional complexity of connecting to the extra terminal restricted commercial application for the design.
Accordingly, the inventor identified a need for a better way of manufacturing tags that require three external terminals and two capacitors.
To address these and other needs, the present inventor devised a unique radio-frequency-identification (RFID) module which uses two capacitors, but only requires two external connections. In one exemplary embodiment, the module includes two external terminals for connection to an antenna coil and an internal terminal for connection to a tap of a dual (center-tapped) capacitor. Other aspects of the invention include components of the module and methods of assembling tags using the module.